JP6229609B2 - Group III nitride semiconductor light emitting device manufacturing method - Google Patents

Description

Technical Field of the specification relates to a method for producing a group III nitride semiconductor light-emitting device. More particularly, it relates to a method for producing low III-nitride semiconductor light emitting device driving voltage.

  In the group III nitride semiconductor light emitting device, there is no electrode material having a work function capable of realizing complete ohmic contact with a p-type contact layer, for example, a p-type GaN layer. Therefore, the p-type contact layer and the p-electrode form a Schottky contact. In order to reduce the contact resistance, it is preferable that the carriers easily exceed the Schottky barrier by the tunnel effect. For this purpose, for example, the p-type contact layer is doped with a high-concentration p-type dopant to thin the Schottky barrier. Further, in order to make it easier for carriers to tunnel through the Schottky barrier, it is preferable that appropriate crystal defects exist in the Schottky barrier. This is because carriers easily tunnel through crystal defects.

  For example, Patent Document 1 discloses a light emitting diode 10 having a second contact layer 62 and a first contact layer 63 having a Mg concentration higher than that of the second contact layer 62 (paragraph [0011] of Patent Document 1). ] And FIG. 1). Thus, it is described that a light emitting diode with a low driving voltage was obtained (see paragraph [0009] of Patent Document 1).

Japanese Patent Application Laid-Open No. 08-097471

  As described above, in order for the carriers to easily escape the Schottky barrier by the tunnel effect, the concentration of the p-type dopant doped into the p-type contact layer, for example, Mg may be increased. For this purpose, it is necessary to increase the concentration of the p-type dopant gas and to incorporate a high concentration of the p-type dopant into the semiconductor crystal. However, immediately after the supply of the p-type dopant gas is started, the dopant concentration of the growing p-type contact layer is lower than the desired dopant concentration. The dopant concentration of the p-type contact layer tends to increase as the film thickness increases, that is, the growth time elapses. Thereby, the dopant concentration in the vicinity of the contact surface in the p-type contact layer can be set to a desired concentration.

  The dopant gas is adsorbed on the inner wall of the chamber by the memory effect. Therefore, it is considered that the gas concentration is not stable immediately after the supply of the p-type dopant gas is started. Therefore, the desired gas concentration is not achieved on the crystal growth surface immediately after the start of supply. Or it is thought that it is based on the property that a group III nitride semiconductor cannot take in p-type dopant easily. Therefore, in order to obtain a desired p-type dopant concentration, the p-type contact layer needs to have a film thickness equal to or larger than the Schottky barrier. For this reason, the electrical resistivity increases due to an increase in an extra series resistance component and the introduction of unintended crystal defects. And a drive voltage will rise. Therefore, in order to manufacture a semiconductor light emitting device having a low electrical resistance, it is important to provide a p-type contact layer having a small film thickness and a high p-type dopant concentration.

The technique of this specification has been made to solve the problems of the conventional techniques described above. That it is an object is to provide a method for producing a low III-nitride semiconductor light emitting device driving voltage.

The method for producing a group III nitride semiconductor light emitting device according to the first aspect includes an n type semiconductor layer forming step of forming an n type semiconductor layer, a light emitting layer forming step of forming a light emitting layer on the n type semiconductor layer, A p-type semiconductor layer forming step of forming a p-type semiconductor layer on the light emitting layer. The p-type semiconductor layer forming step includes a p-type cladding layer forming step of forming a p-type cladding layer on the light emitting layer by supplying a first source gas containing at least a group III element and a dopant gas. A p-type intermediate layer forming step of forming a p-type intermediate layer on the p-type cladding layer by supplying a source gas and a dopant gas, and a supply of the first source gas after the p-type intermediate layer forming step A p-type contact layer is formed on the p-type intermediate layer by supplying a first source gas and a dopant gas after the dopant gas supply step of stopping and supplying the dopant gas and supplying the first source gas and the dopant gas And a contact layer forming step. The molar ratio of the dopant gas to the first source gas in the dopant gas supply step is larger than the molar ratio of the dopant gas to the first source gas in the p-type intermediate layer forming step. The molar ratio of the dopant gas to the first source gas in the p-type contact layer forming step is larger than the molar ratio of the dopant gas to the first source gas in the p-type intermediate layer forming step. The flow rate of the first source gas in the p-type contact layer forming step is smaller than the flow rate of the first source gas in the p-type intermediate layer forming step. The flow rate of the dopant gas in the p-type contact layer forming step is larger than the flow rate of the dopant gas in the p-type intermediate layer forming step. The thickness of the p-type contact layer is not less than 0.5 nm and not more than 10 nm. The Mg concentration of the p-type contact layer is 1 × 10 ²⁰ cm ⁻³ or more and 1 × 10 ²² cm ⁻³ or less. The change rate of the Mg concentration of the p-type contact layer is 5 × 10 ¹⁸ cm ⁻³ · nm ^{−1 to} 1 × 10 ²⁰ cm ⁻³ · nm ⁻¹ .

  In this method for manufacturing a group III nitride semiconductor light emitting device, the concentration of the dopant gas in the furnace of the semiconductor device and in the vicinity of the surface of the semiconductor crystal is increased before the p-type contact layer is formed. That is, the dopant gas is sufficiently filled in the periphery of the growth substrate immediately before the formation of the p-type contact layer. Therefore, Mg is likely to be steeply taken into the p-type contact layer immediately after the growth of the p-type contact layer. Therefore, a p-type contact layer having a high Mg concentration can be realized with a thin film thickness. Therefore, it is possible to form a Schottky barrier in which carriers can easily pass through the tunnel effect. Therefore, a group III nitride semiconductor light emitting device having a low driving voltage can be manufactured.

In the production method of a group III nitride semiconductor light-emitting device in the second embodiment, the flow rate of the dopant gas in the dopant gas supplying step, not multi than the flow rate of the dopant gas in the p-type intermediate layer forming step.

In the production method of a group III nitride semiconductor light-emitting device in the third embodiment, the flow rate of the dopant gas in the dopant gas supply step is not less than the flow rate of the dopant gas in the p-type contact layer formation step.

In the production method of a group III nitride semiconductor light-emitting device in the fourth embodiment, the flow rate of the dopant gas in the dopant gas supplying step, not multi than the flow rate of the dopant gas in the p-type contact layer formation step.

In the Group III nitride semiconductor light-emitting device manufacturing method according to the fifth aspect, the dopant gas supply amount is gradually increased in the dopant gas supply step.

In the Group III nitride semiconductor light-emitting device manufacturing method according to the sixth aspect, the supply amount of the first source gas in the p-type contact layer forming step is set to the supply amount of the first source gas in the p-type intermediate layer formation step. Is equal to

In the method for manufacturing a Group III nitride semiconductor light emitting device according to the seventh aspect, in the p-type intermediate layer forming step and the p-type contact layer forming step, a third source gas containing nitrogen atoms is supplied, and a dopant gas is supplied. In the process, the supply of the third source gas is stopped.

In the method for manufacturing a group III nitride semiconductor light emitting device according to the eighth aspect, the p-type intermediate layer forming step includes a first p-type intermediate layer forming a first p-type intermediate layer on the p-type cladding layer. A forming step, and a second p-type intermediate layer forming step of forming a second p-type intermediate layer on the first p-type intermediate layer.

In the Group III nitride semiconductor light-emitting device manufacturing method according to the ninth aspect, the dopant gas supply step has an implementation period in the range of 1 second to 60 seconds.

In the Group III nitride semiconductor light emitting device manufacturing method according to the tenth aspect, the first source gas is a gas containing a gallium atom as a Group III element. The dopant gas is a gas containing magnesium atoms. Examples of the gas containing gallium atoms include trimethyl gallium (TMG) and triethyl gallium (TEG). Examples of the gas containing a magnesium atom include cyclopentadienyl magnesium (Mg (C ₅ H ₅ ) ₂ ) and bisethylcyclopentadienyl magnesium (EtCp ₂ Mg: Mg (C ₂ H ₅ C ₅ H ₄ ) _2. ).

In the Group III nitride semiconductor light-emitting device manufacturing method according to the eleventh aspect, at least nitrogen gas is supplied as a carrier gas in the p-type intermediate layer forming step. The nitrogen gas occupying the carrier gas is in the range of 30% to 80% in terms of molar ratio.

In the present specification, a method for manufacturing a group III nitride semiconductor light emitting device having a low driving voltage is provided.

It is a schematic block diagram which shows the structure of the light emitting element which concerns on embodiment. It is a figure which shows the structure around the p-type contact layer of the light emitting element which concerns on embodiment. It is a figure for demonstrating the 1st formation method of the p-type contact layer of the light emitting element which concerns on embodiment. It is a figure for demonstrating the 2nd formation method of the p-type contact layer of the light emitting element which concerns on embodiment. It is a figure for demonstrating the 3rd formation method of the p-type contact layer of the light emitting element which concerns on embodiment. It is a figure for demonstrating the 4th formation method of the p-type contact layer of the light emitting element which concerns on embodiment. It is a figure for demonstrating the 5th formation method of the p-type contact layer of the light emitting element which concerns on embodiment. It is a figure for demonstrating the 6th formation method of the p-type contact layer of the light emitting element which concerns on embodiment. It is FIG. (1) for demonstrating the manufacturing method of the light emitting element which concerns on embodiment. It is FIG. (2) for demonstrating the manufacturing method of the light emitting element which concerns on embodiment. It is FIG. (3) for demonstrating the manufacturing method of the light emitting element which concerns on embodiment. It is a graph which shows the relationship between the length of a 2nd supply process (2nd period), and a drive voltage. It is a graph which shows the relationship between the length of a 2nd supply process (2nd period), and the yield by evaluation of electrostatic withstand voltage property. It is a graph which shows the relationship between the film thickness of a p-type contact layer, and the measured value of Mg density | concentration of a p-type contact layer.

  Hereinafter, specific embodiments will be described with reference to the drawings, taking a semiconductor light emitting element and a manufacturing method thereof as examples. However, it is not limited to these embodiments. Moreover, the laminated structure and electrode structure of each layer of the semiconductor light emitting element described later are examples. Of course, a laminated structure different from that of the embodiment may be used. And the thickness of each layer in each figure is shown conceptually and does not indicate the actual thickness.

(First embodiment)
1. Semiconductor Light Emitting Element FIG. 1 shows a schematic configuration of a light emitting element 100 according to this embodiment. The light emitting element 100 is a face-up type semiconductor light emitting element. The light emitting element 100 has a plurality of semiconductor layers made of a group III nitride semiconductor. As shown in FIG. 1, the light emitting device 100 includes a substrate 110, a buffer layer 120, an n-type contact layer 130, an n-side ESD layer 140, an n-side superlattice layer 150, a light-emitting layer 160, and a p-side. It has a superlattice layer 170, a p-type intermediate layer 180, a p-type contact layer 190, a p-electrode P1, and an n-electrode N1.

  On the main surface of the substrate 110, a buffer layer 120, an n-type contact layer 130, an n-side ESD layer 140, an n-side superlattice layer 150, a light emitting layer 160, a p-side superlattice layer 170, p A mold intermediate layer 180 and a p-type contact layer 190 are formed in this order. The n electrode N <b> 1 is formed on the n-type contact layer 130. The p electrode P1 is formed on the p-type contact layer 190. Here, the n-type contact layer 130, the n-side ESD layer 140, and the n-side superlattice layer 150 are n-type semiconductor layers. The p-side superlattice layer 170, the p-type intermediate layer 180, and the p-type contact layer 190 are p-type semiconductor layers. However, these layers may partially include a non-doped layer. Thus, the light emitting device 100 includes an n-type semiconductor layer, a light-emitting layer on the n-type semiconductor layer, a p-type semiconductor layer on the light-emitting layer, a p-electrode P1 on the p-type semiconductor layer, n N-type electrode N1 on the type semiconductor layer.

  The substrate 110 is a growth substrate for forming each of the semiconductor layers on the main surface by MOCVD. And it is good for the main surface to be uneven | corrugated. The material of the substrate 110 is sapphire. In addition to sapphire, materials such as SiC, ZnO, Si, GaN, and AlN may be used.

  The buffer layer 120 is formed on the main surface of the substrate 110. The buffer layer 120 is for forming high-density crystal nuclei on the substrate 110. Thereby, the growth of a semiconductor crystal having a flat surface is promoted. Examples of the material of the buffer layer 120 include AlN, GaN, BN, and TiN.

The n-type contact layer 130 is in contact with the n-electrode N1. The n-type contact layer 130 is formed on the buffer layer 120. The n-type contact layer 130 is n-type GaN. The n-type contact layer 130 has a Si concentration of 1 × 10 ¹⁸ / cm ³ or more. Further, the n-type contact layer 130 may be a plurality of layers having different carrier concentrations. The thickness of the n-type contact layer 130 is, for example, in the range of not less than 1000 nm and not more than 10,000 nm. Of course, other thicknesses may be used.

The n-side ESD layer 140 is an electrostatic withstand voltage layer for preventing electrostatic breakdown of the semiconductor layer. The n-side ESD layer 140 is formed on the n-type contact layer 130. The n-side ESD layer 140 is formed by laminating an i-GaN layer made of non-doped i-GaN and an n-type GaN layer made of n-type GaN doped with Si. The film thickness of the i-GaN layer is, for example, in the range of 5 nm to 500 nm. The film thickness of the n-type GaN layer is, for example, in the range of 10 nm to 50 nm. The Si concentration in the n-type GaN layer is in the range of 1 × 10 ¹⁸ / cm ^{3 to} 5 × 10 ¹⁹ / cm ³ . These numerical ranges are examples, and other values may be used.

  The n-side superlattice layer 150 is a strain relaxation layer for relaxing stress applied to the light emitting layer 160. More specifically, the n-side superlattice layer 150 has a superlattice structure. The n-side superlattice layer 150 is formed by repeatedly laminating an InGaN layer and an n-type GaN layer. The number of repetitions is in the range of 3 to 20 times. However, the number of times may be other than this. The In composition ratio in the InGaN layer of the n-side superlattice layer 150 is, for example, in the range of 2% to 20%. The thickness of the InGaN layer in the n-side superlattice layer 150 is, for example, in the range of not less than 0.2 nm and not more than 9 nm. The thickness of the n-type GaN layer in the n-side superlattice layer 150 is, for example, in the range of 1 nm to 5 nm.

  The light emitting layer 160 is a layer that emits light by recombination of electrons and holes. The light emitting layer 160 is formed on the n-side superlattice layer 150. The light emitting layer 160 has at least a well layer and a barrier layer. For example, an InGaN layer or a GaN layer can be used as the well layer. As the barrier layer, for example, a GaN layer or an AlGaN layer can be used. These are examples, and other AlInGaN layers may be used.

  The p-side superlattice layer 170 is formed on the light emitting layer 160. The p-side superlattice layer 170 is a p-type cladding layer. The p-side superlattice layer 170 is formed by repeatedly forming a stacked body in which, for example, a p-type GaN layer, a p-type AlGaN layer, and a p-type InGaN layer are stacked. The number of repetitions is, for example, 5 times. The thickness of the p-type GaN layer of the p-side superlattice layer 170 is in the range of not less than 0.5 nm and not more than 7 nm. The Al composition ratio of the p-type AlGaN layer of the p-side superlattice layer 170 is in the range of 5% to 40%. The thickness of the p-type AlGaN layer of the p-side superlattice layer 170 is in the range of not less than 0.5 nm and not more than 7 nm. The In composition ratio of the p-type InGaN layer of the p-side superlattice layer 170 is in the range of 1% to 20%. The p-type InGaN layer of the p-side superlattice layer 170 has a thickness in the range of 0.5 nm to 7 nm. These numerical values are merely examples. Therefore, other numerical values may be used. Moreover, a different structure may be sufficient.

  The p-type intermediate layer 180 is formed on the p-side superlattice layer 170. The p-type intermediate layer 180 includes a first p-type GaN layer 181 and a second p-type GaN layer 182. The first p-type GaN layer 181 is a first p-type intermediate layer. The second p-type GaN layer 182 is a second p-type intermediate layer. Both the first p-type GaN layer 181 and the second p-type GaN layer 182 are layers made of GaN doped with Mg. The first p-type GaN layer 181 is formed on the p-side superlattice layer 170. The second p-type GaN layer 182 is formed on the first p-type GaN layer 181. The second p-type GaN layer 182 is in contact with the p-type contact layer 190.

  The p-type contact layer 190 is a semiconductor layer that is electrically connected to the p-electrode P1. Therefore, the p-type contact layer 190 is in contact with the p electrode P1. The p-type contact layer 190 is formed on the second p-type GaN layer 182 of the p-type intermediate layer 180. The p-type contact layer 190 is a layer made of p-type GaN doped with Mg.

The p electrode P1 is formed on the p-type contact layer 190. The p-electrode P1 is in contact with the p-type contact layer 190. The material of the p electrode P1 is ITO. In addition to ITO, transparent conductive oxides such as ICO, IZO, ZnO, TiO ₂ , NbTiO ₂ , and TaTiO ₂ can be used. Further, a metal electrode made of a metal such as Ni, Au, Ag, Co, or In may be formed on the p-electrode P1. Alternatively, other electrodes may be formed on the p-electrode P1.

  The n electrode N <b> 1 is formed on the n-type contact layer 130. The n electrode N1 is in contact with the n-type contact layer 130. The n electrode N1 is formed by sequentially forming V and Al from the n-type contact layer 130 side. Ti and Al may be formed in order. Ti and Au may be formed in order.

2. p-type GaN layer and p-type contact layer 2-1. FIG. 2 is an enlarged view showing the periphery of the p-type contact layer 190. FIG. As shown in FIG. 2, the p-type contact layer 190 has a first surface 190a and a second surface 190b. The first surface 190a of the p-type contact layer 190 is in contact with the p-electrode P1. The second surface 190 b of the p-type contact layer 190 is in contact with the second p-type GaN layer 182.

2-2. p-Type Intermediate Layer The first p-type GaN layer 181 and the second p-type GaN layer 182 are p-type GaN doped with Mg. However, the Mg concentration differs between the first p-type GaN layer 181 and the second p-type GaN layer 182. The Mg concentration of the first p-type GaN layer 181 is in the range of 1 × 10 ¹⁸ / cm ^{3 to} 4 × 10 ¹⁹ / cm ³ . The Mg concentration of the second p-type GaN layer 182 is in the range of 5 × 10 ¹⁹ / cm ^{3 to} 1 × 10 ²⁰ / cm ³ . The film thickness of the first p-type GaN layer 181 is in the range of 5 nm to 250 nm. The film thickness of the second p-type GaN layer 182 is in the range of 5 nm to 250 nm.

2-3. p-type Contact Layer The Mg concentration of the p-type contact layer 190 is in the range of 1 × 10 ²⁰ / cm ^{3 to} 1 × 10 ²² / cm ³ . The thickness of the p-type contact layer 190 is in the range of not less than 0.5 nm and not more than 50 nm. Preferably, it exists in the range of 0.5 nm or more and 10 nm or less. More preferably, it is in the range of 1 nm or more and 8 nm or less.

2-4. Rate of change in Mg concentration in the p-type contact layer In the p-type contact layer 190, the Mg concentration increases as it approaches the p-electrode P1 side from the first p-type GaN layer 181 side, as will be described later. The Mg concentration change rate X in the p-type contact layer 190 is given by the following equation.
X = (D1-D2) / Th1 (1)
D1: Mg concentration in the p-type contact layer (on the first surface 190a side)
D2: Mg concentration in the p-type contact layer (second surface 190b side)
Th1: Film thickness of the p-type contact layer Thus, the Mg concentration change rate X is the Mg concentration from the contact surface with the p-type intermediate layer 180 to the contact surface with the p-electrode P1 in the p-type contact layer 190. It is the rate of change.

And it is preferable that the change rate X of Mg density | concentration satisfy | fills following Formula.
5 × 10 ¹⁸ ≦ X ≦ 1 × 10 ²⁰ (2)
X: Rate of change of Mg concentration (cm ^-3 · nm ^-1 )
Thereby, in the p-type contact layer 190, the film thickness is thin and the Mg concentration is suitable.

Preferably, the Mg concentration change rate X satisfies the following equation.
5 × 10 ¹⁸ ≦ X ≦ 5 × 10 ¹⁹ (3)
X: Rate of change of Mg concentration (cm ^-3 · nm ^-1 )
More preferably, the change rate X of the Mg concentration may satisfy the following formula.
5 × 10 ¹⁸ ≦ X ≦ 2 × 10 ¹⁹ (4)
X: Rate of change of Mg concentration (cm ^-3 · nm ^-1 )

3. Method for Forming p-type Intermediate Layer and p-type Contact Layer Here, a process for forming the p-type GaN layer and the p-type contact layer will be described. The p-type contact layer forming step is a step of forming the p-type contact layer 190 using a vapor phase growth method such as an MOCVD method. This p-type contact layer forming process has many variations. These forming methods will be described in order.

In each forming method, a common material gas can be used. The source gas has a first source gas, a second source gas, and a third source gas. The first source gas is a source gas containing gallium atoms (Ga). Examples of the first source gas include trimethyl gallium (TMG) and triethyl gallium (TEG). The second source gas is a dopant gas containing Mg atoms. Examples of the second source gas include cyclopentadienyl magnesium (Mg (C ₅ H ₅ ) ₂ ) and bisethylcyclopentadienyl magnesium (EtCp ₂ Mg: Mg (C ₂ H ₅ C ₅ H ₄ ) ₂ ). Is mentioned. The third source gas is a source gas containing nitrogen atoms (N). Examples of the third source gas include ammonia (NH ₃ ) and hydrazine (N ₂ H ₄ ).

3-1. First Forming Method FIG. 3 is a timing chart showing the amount of source gas supplied in the p-type contact layer forming step of the first forming method. Therefore, in addition to the one shown in FIG. 3, a carrier gas such as nitrogen gas or hydrogen gas is used.

  As shown in FIG. 3, the p-type contact layer forming step includes a first supply step (p-type intermediate layer forming step), a second supply step (dopant gas supply step), and a third supply step (p Mold contact layer forming step). The first supply step (p-type intermediate layer forming step) is a step for forming the second p-type GaN layer 182 of the p-type intermediate layer 180. The second supply step (dopant gas supply step) is a step for filling the dopant gas inside the chamber for growing the semiconductor, that is, on the surface of the semiconductor crystal. The third supply process (p-type contact layer forming process) is a process for forming the p-type contact layer 190.

In the first supply step, TMG, NH ₃ , and Mg (C ₅ H ₅ ) ₂ are supplied in the first period TA1. In the second supply step, the supply of TMG is stopped and NH ₃ and Mg (C ₅ H ₅ ) ₂ are supplied in the second period TA2. In the third supply step, TMG, NH ₃ , and Mg (C ₅ H ₅ ) ₂ are supplied in the third period TA3.

3-1-1. First supply step (p-type intermediate layer forming step)
As shown in FIG. 3, TMG, NH ₃ , and Mg (C ₅ H ₅ ) ₂ are supplied in the first period TA1. Thereby, the second p-type GaN layer 182 doped with Mg grows. In the first period TA1, TMG is supplied by the supply amount SA1. Further, Mg (C ₅ H ₅ ) ₂ is supplied by the supply amount SB1. Then, NH ₃ is supplied by the supply amount SC1.

3-1-2. Second supply process (dopant gas supply process)
In the second period TA2, supply of TMG is stopped and Mg (C ₅ H ₅ ) ₂ is supplied. That is, the supply amount of TMG is zero. In the second period TA2, Mg (C ₅ H ₅ ) ₂ is supplied by the supply amount SB2. The value of the supply amount SB2 is larger than the value of the supply amount SB1 in the first period TA1. That is, the ratio of the dopant gas to the first source gas in the dopant gas supply step is larger than the ratio of the dopant gas to the first source gas in the p-type intermediate layer forming step. Further, the supply amount of the dopant gas in the third period TA3 is the same as that in the second period TA2. Therefore, the ratio of the dopant gas to the first source gas in the p-type contact layer forming step is larger than the ratio of the dopant gas to the first source gas in the p-type intermediate layer forming step. Further, NH ₃ is supplied by the supply amount SC1.

Since TMG is not supplied, the GaN layer does not grow in the second period TA2. Then, so that the Mg (C ₅ H _{5) 2} is filled into the chamber. Then, the concentration of Mg (C ₅ H ₅ ) ₂ around the substrate 110 increases to some extent. The Mg degree of (C ₅ H _{5) 2} of filling the time and the second period TA2, depends on the supply amount per Mg (C ₅ H _{5) 2} unit time in the second period TA2. It is also considered to depend on the volume of the chamber. For example, the time of the second period TA2 is 1 second or more and 60 seconds or less. Preferably, it is 3 seconds or more and 30 seconds or less. More preferably, it is 5 seconds or more and 20 seconds or less. However, these depend on the gas flow rate and chamber volume.

3-1-3. Third supply step (p-type contact layer forming step)
In the third period TA3, the supply of TMG is started again. In the third period TA3, TMG is supplied by the supply amount SA2. In the second period TA2, Mg (C ₅ H ₅ ) ₂ is supplied by the supply amount SB2. Further, NH ₃ is supplied by the supply amount SC1. The value of the supply amount SA2 of TMG is smaller than the value of the supply amount SA1 in the first period TA1. Thus, the supply amount of TMG in the third period TA3 is smaller than the supply amount of TMG in the first period TA1.

Therefore, the deposition rate in the third period TA3 is slower than the deposition rate in the first period TA1. Thereby, in the third supply step, the p-type contact layer 190 can be formed with a thin film thickness as intended. In addition, the supply amount of Mg (C ₅ H ₅ ) ₂ in the third period TA3 is larger than the supply amount of Mg (C ₅ H ₅ ) ₂ in the first period TA1. Therefore, the Mg raw material is filled in the chamber in the second period TA2. Therefore, a GaN layer with a high Mg concentration can be deposited.

In the third supply step, the ratio of the second source gas to the first source gas is larger than the ratio of the second source gas to the first source gas in the first supply step. That is, the ratio of Mg (C ₅ H ₅ ) _{2 to} TMG in the third period TA 3 is larger than the ratio of Mg (C ₅ H ₅ ) _{2 to} TMG in the first period TA 1.

  And the flow volume of the dopant gas in a dopant gas supply process is larger than the flow volume of the dopant gas in a p-type intermediate | middle layer formation process. Further, the flow rate of the dopant gas in the p-type contact layer forming step is larger than the flow rate of the dopant gas in the p-type intermediate layer forming step.

  Note that the substrate temperature in the p-type contact layer forming step is in the range of 800 ° C. or more and 1200 ° C. or less. The substrate temperature may be maintained at a constant temperature within this temperature range from the first period TA1 to the third period TA3.

3-2. Second Forming Method FIG. 4 is a timing chart showing the supply amount of the source gas in the p-type contact layer forming step of the second forming method. Similar to the first formation method, the second formation method includes a first supply step, a second supply step, and a third supply step. Here, the first supply process and the third supply process in the second forming method are the same as those in the first forming method.

The difference from the first formation method is the supply amount of Mg (C ₅ H ₅ ) ₂ in the second supply step. In the second supply step, Mg (C ₅ H ₅ ) ₂ is supplied by the supply amount SB1. That is, the supply amount SB1 of Mg (C ₅ H ₅ ) ₂ is common between the first period TA1 and the second period TA2. The value of the supply amount SB1 of Mg (C ₅ H ₅ ) ₂ in the second supply process in the second formation method is smaller than that in the first formation process.

  And the flow volume of the dopant gas in a dopant gas supply process is less than the flow volume of the dopant gas in a p-type contact layer formation process. Further, the flow rate of the dopant gas in the p-type contact layer forming step is larger than the flow rate of the dopant gas in the p-type intermediate layer forming step.

3-3. Third Forming Method FIG. 5 is a timing chart showing the amount of source gas supplied in the p-type contact layer forming step of the third forming method. Similar to the first formation method, the third formation method includes a first supply process, a second supply process, and a third supply process. Here, the first supply process and the third supply process in the third forming method are the same as those in the first forming method.

The difference from the first formation method is the supply amount of Mg (C ₅ H ₅ ) ₂ in the second supply step. In the second supply step, Mg (C ₅ H ₅ ) ₂ is supplied by the supply amount SB3. The value of the supply amount SB3 is larger than the value of the supply amount SB2 of Mg (C ₅ H ₅ ) ₂ in the third period TA3. That is, the ratio of the dopant gas to the first source gas in the dopant gas supply step is larger than the ratio of the dopant gas to the first source gas in the p-type contact layer forming step. Further, the value of the supply amount SB3 is larger than the value of the supply amount SB2 of Mg (C ₅ H ₅ ) ₂ in the second supply step in the first forming method.

Therefore, more of Mg (C ₅ H ₅ ) ₂ and their reaction gas can be filled into the chamber. The concentrations of Mg (C ₅ H ₅ ) ₂ and their reaction gases around the substrate 110 at the start of the second p-type contact layer forming step are sufficiently high.

  The flow rate of the dopant gas in the dopant gas supply step is larger than the flow rate of the dopant gas in the p-type contact layer formation step. Further, the flow rate of the dopant gas in the p-type contact layer forming step is larger than the flow rate of the dopant gas in the p-type intermediate layer forming step.

3-4. Fourth Forming Method FIG. 6 is a timing chart showing the amount of source gas supplied in the p-type contact layer forming step of the fourth forming method. Similar to the first forming method, the fourth forming method includes a first supplying step, a second supplying step, and a third supplying step. Here, the first supply process and the third supply process in the fourth formation method are the same as those in the first formation method.

The difference from the first formation method is the supply amount of Mg (C ₅ H ₅ ) ₂ in the second supply step. In the second supply step, Mg (C ₅ H ₅ ) ₂ is gradually increased from the supply amount SB1 to the supply amount SB2. That is, in the dopant gas supply step, the supply amount of the dopant gas is gradually increased with time. Even in such a case, the p-type contact layer 190 can be preferably formed.

In FIG. 6, Mg (C ₅ H ₅ ) ₂ is supplied at the supply amount SB2 at the end of the second supply step. However, the supply amount of Mg (C ₅ H ₅ ) ₂ is gradually increased after the start of the second period TA2, and a constant supply is made from the middle of the second period TA2 to the end of the second period TA2. Mg (C ₅ H ₅ ) ₂ may be supplied in an amount SB2.

3-5. Fifth Forming Method FIG. 7 is a timing chart showing the supply amount of the source gas in the p-type contact layer forming step of the fifth forming method. The fifth formation method includes a first supply step, a second supply step, and a third supply step, as in the first formation method. Here, the first supply process and the second supply process in the fifth forming method are the same as those in the first forming method.

  A difference from the first forming method is a supply amount of TMG in the third supply process. In the third supply step, TMG is supplied by the supply amount SA1. That is, the TMG supply amount SA1 in the third supply step is the same as the TMG supply amount SA1 in the first supply step. Therefore, the film formation rate in the third supply step is substantially equal to the film formation rate in the first supply step. That is, the supply amount of the first source gas in the p-type contact layer formation step is made equal to the supply amount of the first source gas in the p-type intermediate layer formation step.

3-6. Sixth Forming Method FIG. 8 is a timing chart showing the amount of source gas supplied in the p-type contact layer forming step of the sixth forming method. Similar to the first forming method, the sixth forming method includes a first supplying step, a second supplying step, and a third supplying step. Here, the first supply process and the third supply process in the sixth formation method are the same as those in the first formation method.

The difference from the first forming method is the supply amount of NH ₃ in the second supply step. In the sixth formation method, NH ₃ is not supplied in the second supply step, that is, the second period TA2. In the second supply step, the supply of NH ₃ may be stopped because no p-type GaN is grown. That is, in the p-type intermediate layer forming step and the p-type contact layer forming step, the third source gas containing N is supplied, and in the dopant gas supply step, the supply of the third source gas is stopped. This makes it possible to reduce the amount of NH _3. That is, in the p-type intermediate layer formation step and the p-type contact layer formation step, the third source gas containing nitrogen atoms is supplied, and in the dopant gas supply step, the supply of the third source gas is stopped.

3-7. From the first formation method to the sixth formation method In the first formation method to the sixth formation method described above, the molar ratio of the dopant gas to the first source gas in the dopant gas supply step is p-type. It is larger than the molar ratio of the dopant gas to the first source gas in the intermediate layer forming step. Further, the molar ratio of the dopant gas to the first source gas in the p-type contact layer forming step is larger than the molar ratio of the dopant gas to the first source gas in the p-type intermediate layer forming step.

4). Manufacturing Method of Semiconductor Light-Emitting Element Here, a manufacturing method of the light-emitting element 100 according to this embodiment will be described. In the present embodiment, crystals of each semiconductor layer are epitaxially grown by metal organic chemical vapor deposition (MOCVD). Therefore, this manufacturing method includes an n-type semiconductor layer forming step for forming an n-type semiconductor layer, a light-emitting layer forming step for forming a light-emitting layer on the n-type semiconductor layer, and a p-type semiconductor layer on the light-emitting layer. A p-type semiconductor layer forming step for forming; a p-electrode forming step for forming a p-electrode on the p-type semiconductor layer; and an n-electrode forming step for forming an n-electrode on the n-type semiconductor layer. The p-type semiconductor layer forming step includes a p-type cladding layer forming step of forming a p-type cladding layer on the light emitting layer by supplying a first source gas containing at least a group III element and a dopant gas. A p-type intermediate layer forming step of forming a p-type intermediate layer on the p-type cladding layer by supplying a source gas and a dopant gas, and a supply of the first source gas after the p-type intermediate layer forming step A p-type contact layer is formed on the p-type intermediate layer by supplying a first source gas and a dopant gas after the dopant gas supply step of stopping and supplying the dopant gas and supplying the first source gas and the dopant gas And a contact layer forming step.

  The p-type semiconductor layer forming step includes a p-type intermediate layer forming step of forming a p-type GaN layer by supplying a first source gas containing at least Ga and a dopant gas containing Mg, and a first source gas. And a p-type contact layer forming step of forming a p-type contact layer by supplying at least a first source gas and a dopant gas.

Examples of the carrier gas used here include hydrogen (H ₂ ), nitrogen (N ₂ ), or a mixed gas of hydrogen and nitrogen (H ₂ + N ₂ ). Any of these may be used in each step described later unless otherwise specified. Ammonia gas (NH ₃ ) is used as a nitrogen source. Trimethylgallium (Ga (CH ₃ ) ₃ : “TMG”) is used as the Ga source. Trimethylindium (In (CH ₃ ) ₃ : “TMI”) is used as the In source. Trimethylaluminum (Al (CH ₃ ) ₃ : “TMA”) is used as the Al source. Silane (SiH ₄ ) is used as the n-type dopant gas. As the p-type dopant gas, cyclopentadienyl magnesium (Mg (C ₅ H ₅ ) ₂ : hereinafter, sometimes referred to as “Cp ₂ Mg”) is used.

4-1. n-type semiconductor layer forming step 4-1-1. Step of forming n-type contact layer First, the substrate 110 is cleaned using hydrogen gas. Next, the buffer layer 120 is formed on the main surface of the substrate 110. Thereafter, an n-type contact layer 130 is formed on the buffer layer 120. The substrate temperature at this time is in the range of 1000 ° C. or more and 1200 ° C. or less.

4-1-2. Step of forming n-side ESD layer Next, the n-side ESD layer 140 is formed on the n-type contact layer 130. In order to form the i-GaN layer, the supply of silane (SiH ₄ ) is stopped. The substrate temperature at this time is in the range of 750 ° C. or more and 950 ° C. or less. In order to form n-type GaN, silane (SiH ₄ ) is supplied again. The substrate temperature at this time is the same temperature as the temperature for forming the i-GaN layer, that is, within the range of 750 ° C. or more and 950 ° C. or less.

4-1-3. Step of forming n-side superlattice layer Next, the n-side superlattice layer 150 is formed on the n-side ESD layer 140. For example, an InGaN layer and an n-type GaN layer are repeatedly stacked. The substrate temperature in that case is in the range of 700 ° C. or more and 950 ° C. or less.

4-2. Next, the light emitting layer 160 is formed on the n-side superlattice layer 150. For example, an InGaN layer, a GaN layer, and an AlGaN layer are repeatedly stacked. The substrate temperature at this time is set in the range of 700 ° C. or higher and 900 ° C. or lower.

4-3. p-type semiconductor layer forming step 4-3-1. p-side superlattice layer forming step (p-type cladding layer forming step)
Next, the p-side superlattice layer 170 is formed on the light emitting layer 160. For example, a p-type GaN layer, a p-type AlGaN layer, and a p-type InGaN layer are repeatedly stacked. Cyclopentadienyl magnesium (Mg (C ₅ H ₅ ) ₂ ) may be used as the dopant gas. Thereby, the laminated body shown in FIG. 9 is obtained.

4-3-2. p-type intermediate layer forming step In the p-type intermediate layer forming step and the p-type contact layer forming step, any one of the above-described first forming method to sixth forming method is used. The p-type intermediate layer forming step includes a first p-type intermediate layer forming step of forming a first p-type intermediate layer on the p-side superlattice layer 170 and a second p-type intermediate layer on the first p-type intermediate layer. A second p-type intermediate layer forming step of forming the p-type intermediate layer.

  In this step, the first p-type GaN layer 181 is formed on the p-side superlattice layer 170. When the first p-type GaN layer 181 is formed, no p-type dopant gas is supplied. However, the first p-type GaN layer 181 may be doped with Mg due to the memory effect of the dopant gas used in the p-side superlattice layer forming step. Then, a second p-type GaN layer 182 is formed on the first p-type GaN layer 181. When forming the second p-type GaN layer 182, a p-type dopant gas is supplied.

In forming these p-type intermediate layers 180, at least nitrogen gas is supplied as a carrier gas. For example, a mixed gas of H ₂ and N ₂ is used. Nitrogen gas in the carrier gas is in a range of 20% to 80% in terms of molar ratio. Preferably, it is in the range of 30% or more and 80% or less by molar ratio. More preferably, it is in the range of 40% or more and 70% or less by molar ratio.

  Here, hydrogen gas promotes migration of constituent atoms. Therefore, the surface flatness of the layer is improved. Instead, hydrogen atoms may be incorporated into the crystal and bind to Mg. In this case, the activation of Mg is inhibited. On the other hand, nitrogen gas inhibits the decomposition of crystals. That is, it is possible to prevent the nitrogen atom from being detached from the crystal.

4-3-3. Next, a p-type contact layer 190 is formed on the p-type intermediate layer 180. Further, at least hydrogen gas is supplied as a carrier gas. Thereby, the surface flatness of the p-type contact layer 190 is improved. The substrate temperature is set in the range of 800 ° C. or higher and 1200 ° C. or lower. Thereby, as shown in FIG. 10, each semiconductor layer is stacked on the substrate 110.

4-4. Electrode Formation Step Next, the p electrode P <b> 1 is formed on the p-type contact layer 190. Then, as shown in FIG. 11, the n-type contact layer 130 is exposed across a part of the semiconductor layer from the p-type contact layer 190 side by laser or etching. And n electrode N1 is formed in the exposed location. Either the p-electrode P1 formation step or the n-electrode N1 formation step may be performed first.

4-5. Other Steps In addition to the above steps, other steps such as a step of covering the element with an insulating film and a heat treatment step may be performed. Thus, the light emitting device 100 of FIG. 1 is manufactured.

5. Advantageous Effects of the Present Embodiment In the method for manufacturing the light emitting element 100 according to the present embodiment, the second formation of the semiconductor layer is stopped and the dopant gas is supplied between the first period TA1 and the third period TA3. It has a period TA2. Therefore, the p-type contact layer 190 of the light emitting device 100 manufactured by this manufacturing method can realize a high Mg concentration with a small film thickness. Accordingly, it is considered that a Schottky barrier is formed between the p-type contact layer 190 and the p-electrode P1 so that the barrier is thin and easy to tunnel. That is, the driving voltage of the light emitting element 100 is lower than that of the conventional light emitting element.

  In addition, in the method for manufacturing the light emitting element 100 according to the present embodiment, the film formation rate in the third supply step can be sufficiently slowed down. Therefore, it is easy to control the film thickness of the p-type contact layer 190 of the light emitting element 100. Therefore, the variation in the drive voltage for each lot is smaller than in the conventional case.

6). Modification 6-1. Combination In this embodiment, the p-type contact layer forming step has been described from the first forming method to the sixth forming method. These may be freely combined.

6-2. Substrate temperature In this embodiment, the substrate temperature in the p-type contact layer forming step is constant. However, the substrate temperature may be raised during the p-type contact layer forming step. For example, the substrate temperature is raised during the second period TA2. Thereby, Mg easily enters the p-type contact layer 190. However, the substrate temperature is preferably in the range of 800 ° C. or higher and 1200 ° C. or lower.

6-3. Repetitive formation of the peripheral structure of the p-type contact layer The first p-type GaN layer 181, the second p-type GaN layer 182, and the p-type contact layer 190 of this embodiment may be repeatedly formed. The number of repetitions is in the range of 2 to 100 times.

6-4. Flip chip type, substrate lift-off type In this embodiment, the face-up type light emitting device 100 is applied. However, it is of course applicable to other semiconductor light emitting elements. For example, the present invention can naturally be applied to a flip chip having a light extraction surface on the substrate side or a substrate lift-off type semiconductor light emitting device from which a growth substrate is removed.

6-5. Number of p-type Intermediate Layers In this embodiment, the number of p-type intermediate layers 180 is two layers in which a first p-type GaN layer 181 and a second p-type GaN layer 182 are stacked. However, it may be a single layer. Moreover, three or more layers may be sufficient.

6-6. Types of p-type intermediate layer In the present embodiment, a first p-type GaN layer 181 and a second p-type GaN layer 182 are stacked as the p-type intermediate layer 180. However, other p-type group III nitride semiconductors other than p-type GaN may be applied as the p-type intermediate layer 180.

7). Summary of the Present Embodiment As described in detail above, the light emitting device 100 of the present embodiment has the p-type contact layer 190 that is thin and has a high Mg concentration. For this reason, the contact resistance between the p-electrode P1 and the p-type contact layer 190 is small. Therefore, a semiconductor light emitting device with a low driving voltage is realized.

  In addition, the method for manufacturing the semiconductor light emitting device of this embodiment has a second period TA2. Then, the Mg concentration of the p-type contact layer 190 can be easily controlled by adjusting the length of the second period TA2 or the amount of TMG supplied during that period.

  The embodiment described above is merely an example. Therefore, naturally, various improvements and modifications can be made without departing from the scope of the invention. The laminated structure of the laminated body is not necessarily limited to that shown in the drawing. You may select arbitrarily, such as a laminated structure and the repetition frequency of each layer. Moreover, it is not restricted to a metal organic chemical vapor deposition method (MOCVD method). Any other method may be used as long as the crystal is grown using a carrier gas.

1. Driving voltage 1-1. Sample Preparation The p-type intermediate layer 180 and the p-type contact layer 190 were formed by the first forming method described in the embodiment. Specifically, the semiconductor light emitting element was manufactured by changing the length of the second period TA2 in the second supply step. And the drive voltage was measured with respect to the light emitting element manufactured by changing the length of 2nd period TA2.

1-2. Experimental Results FIG. 12 is a graph showing the relationship between the time length of the second supply process and the drive voltage. The horizontal axis in FIG. 12 represents the length of time of the second supply process. The vertical axis in FIG. 12 is the drive voltage. In FIG. 12, the relative values are plotted with the drive voltage when the time of the second supply step is 0 second as the reference 1.

  As shown in FIG. 12, when the duration of the second supply process was 10 seconds, the drive voltage was 0.993. That is, the drive voltage was reduced by 0.7% by performing the second supply process for 10 seconds. Further, when the length of time of the second supply process was 20 seconds, the drive voltage was 0.998. In other words, the drive voltage was reduced by 0.2% by performing the second supply process for 20 seconds. As described above, the drive voltage is improved by performing the second supply step.

In FIG. 12, the light emitting element in which the second supply process was performed for 20 seconds had a drive voltage higher than that in which the first supply process was performed for 10 seconds. This is considered to be because when the length of the second period TA2 of the second supply process is increased, the Mg concentration of the p-type contact layer 190 is increased, and the crystal quality is deteriorated. The Mg concentration in the p-type contact layer 190 is not limited to the length of the first period TA1 of the first supply process, but the supply concentration of the dopant gas containing Mg in the first supply process, and the p-type contact layer It depends on the supply concentration of the dopant gas containing Mg in the forming step. Therefore, in order to achieve a desired Mg concentration in the p-type contact layer 190, the second period TA2, the supply amount SB2, SB3 of Mg (C ₅ H ₅ ) _{2 and} the like may be appropriately controlled. These numerical values are not limited to specific numerical values. However, in order to shorten the cycle time and improve the production efficiency, the time of the second period TA2 is preferably 1 second or more and 60 seconds or less. Preferably, it is 3 seconds or more and 30 seconds or less. More preferably, it is 5 seconds or more and 20 seconds or less.

2. Electrostatic pressure resistance 2-1. Preparation of Sample An experimental sample was prepared in the same manner as in the experiment for the driving voltage described above.

2-2. Experimental Results FIG. 13 is a graph showing the relationship between the length of time of the second supply process and the yield by evaluation of electrostatic withstand voltage. The horizontal axis in FIG. 13 represents the length of time of the second supply process. The vertical axis in FIG. 13 represents the yield by evaluation of electrostatic withstand voltage.

  As shown in FIG. 13, when the time length of the second supply process was set to 0 second, the yield according to the evaluation of electrostatic withstand voltage was 0.897. When the length of time of the second supply process was 10 seconds, the yield based on the evaluation of electrostatic withstand voltage was 0.982. When the length of time of the second supply process was 20 seconds, the yield based on the evaluation of electrostatic withstand voltage was 0.974.

  Thus, when the duration of the second supply process was set to 10 seconds, the yield based on the evaluation of electrostatic withstand voltage improved by 0.085 (8.5%). Thus, when the duration of the second supply process was set to 20 seconds, the yield based on the evaluation of electrostatic withstand voltage improved by 0.077 (7.7%).

  Thus, in the electrostatic withstand voltage test, even when the time length of the second supply process was 10 seconds and the time length of the second supply process was 20 seconds, it was improved to the same extent. . However, the light emitting element in which the time length of the second supply process was 10 seconds was improved over the light emitting element in which the time length of the second supply process was 20 seconds.

Increasing the length of the second period TA2 of the second supply step increases the Mg concentration of the p-type contact layer 190. As a result, the crystallinity of the p-type contact layer 190 is deteriorated, and it is considered that the electrostatic withstand voltage is lowered. This is considered to be because when the length of the second period TA2 of the second supply process is increased, the Mg concentration of the p-type contact layer 190 is increased, and the crystal quality is deteriorated. The Mg concentration in the p-type contact layer 190 is not limited to the length of the first period TA1 of the first supply process, but the supply concentration of the dopant gas containing Mg in the first supply process, and the p-type contact layer It depends on the supply concentration of the dopant gas containing Mg in the forming step. Therefore, in order to achieve a desired Mg concentration in the p-type contact layer 190, the second period TA2, the supply amount SB2, SB3 of Mg (C ₅ H ₅ ) _{2 and} the like may be appropriately controlled. These numerical values are not limited to specific numerical values. However, in order to shorten the cycle time and improve the production efficiency, the time of the second period TA2 is preferably 1 second or more and 60 seconds or less. Preferably, it is 3 seconds or more and 30 seconds or less. More preferably, it is 5 seconds or more and 20 seconds or less.

3. Mg concentration of p-type contact layer 3-1. Preparation of Sample First, a buffer layer 120, an n-type contact layer 130, an n-side ESD layer 140, an n-side superlattice layer 150, a light emitting layer 160, and a p-side superlattice layer 170 are formed on a sapphire substrate. A semiconductor layer corresponding to was formed. Then, a semiconductor layer corresponding to the p-type intermediate layer 180 and the p-type contact layer 190 was formed thereon by the first forming method described in the embodiment. Specifically, the second period TA2 in the second supply step was manufactured with a length of 10 seconds (Example) and with a length of 0 seconds (Comparative Example). Then, the length of the third period TA3 was changed. As a result, a plurality of samples with different thicknesses of the p-type contact layer were produced. Note that changing the third period TA3 means changing the film thickness of the p-type contact layer.

3-2. Measurement Method For these samples prepared by changing the second period TA2 and the third period TA3, the Mg concentration contained in the p-type contact layer was measured using a glow discharge luminescence surface analyzer (GDS).

3-3. Experimental results Table 1 shows the experimental results. In the Example, the dopant gas supply process (2nd supply process) was implemented. In the comparative example, the dopant gas supply process (second supply process) was not performed. For the Mg concentration measured by GDS, the case of Example 1 was set to 1, which is a reference value. In Example 1, the thickness of the p-type contact layer is set to 21 mm, and the dopant gas supply step (second supply step) is performed for 10 seconds.

  As shown in Table 1, in Example 1-4, the Mg concentration (relative value) was 1 or more. On the other hand, in Comparative Example 1-6, the Mg concentration (relative value) was less than 1. That is, in Example 1-4 which implemented the dopant gas supply process, Mg density | concentration is high compared with Comparative Example 1-6. That is, by performing the dopant gas supply step, the degree of Mg incorporation into the p-type contact layer is improved.

  FIG. 14 is a graph showing the relationship between the film thickness of the p-type contact layer in Table 1 and the Mg concentration of the p-type contact layer. As shown in FIG. 14, in the comparative example, the Mg concentration is not so high in the region where the p-type contact layer is thin. Then, the Mg concentration increases as the thickness of the p-type contact layer is increased. In the comparative example, Mg is difficult to be taken into the p-type contact layer at the initial stage of the p-type contact layer forming step. As the growth proceeds and the film thickness increases, the Mg concentration of the p-type contact layer increases.

  In the comparative example, when the thickness of the p-type contact layer is 100 mm or less, a slight difference in the thickness of the p-type contact layer affects the Mg concentration. Therefore, the characteristics of the p-type contact layer tend to vary depending on the manufacturing conditions. Thus, in the comparative example, it is difficult to control the Mg concentration when the thickness of the p-type contact layer is 100 mm or less. As a result of this variation, device characteristics may become unstable. Further, as shown in FIG. 14, in order to obtain a p-type contact layer with a high Mg concentration, a certain thickness is required. Therefore, in order to obtain a p-type contact layer having a sufficient Mg concentration, the p-type contact layer must be designed to have a large thickness. Increasing the thickness of the p-type contact layer increases the electrical resistance of the p-type contact layer.

  As shown in FIG. 14, in Example 1-4, the Mg concentration of the p-type contact layer is substantially constant without depending on the film thickness of the p-type contact layer. The Mg concentration of the p-type contact layer in Example 1-4 is sufficiently higher than that in Comparative Example 1-6. In the region where the thickness of the p-type contact layer is 5 to 100 mm, there is a difference between the example and the comparative example. In the region where the thickness of the p-type contact layer is 5 to 80 mm, the difference between the example and the comparative example is large to some extent. In the region where the thickness of the p-type contact layer is 5 to 50 mm, the difference between the example and the comparative example is very large.

  Therefore, by using the method for manufacturing a semiconductor light emitting element described in the embodiment, a p-type contact layer that is sufficiently thin and has a high Mg concentration can be formed. For this reason, the drive voltage of the light emitting element 100 of the embodiment is sufficiently low.

3-4. Rate of change in Mg concentration The rate of change in Mg concentration of the p-type contact layer in the comparative example was about 1 × 10 ¹⁸ (cm ⁻³ · nm ⁻¹ ). On the other hand, the change rate of the Mg concentration of the p-type contact layer in the example was about 5 × 10 ¹⁸ (cm ⁻³ · nm ⁻¹ ). Further, by changing the conditions of the dopant gas supply step and the p-type contact layer formation step, it is possible to control the rate of change of the Mg concentration to about 1 × 10 ²⁰ (cm ⁻³ · nm ⁻¹ ). Conditions for increasing the rate of change in Mg concentration include, for example, increasing the second period TA2, increasing the dopant gas supply amounts SB2 and SB3, and decreasing the TMG supply amount SA2. The Mg concentration of the p-type contact layer is in the range of 1 × 10 ²⁰ / cm ^{3 to} 1 × 10 ²² / cm ³ .

DESCRIPTION OF SYMBOLS 100 ... Light emitting element 110 ... Substrate 120 ... Buffer layer 130 ... n-type contact layer 140 ... n-side ESD layer 150 ... n-side superlattice layer 160 ... Light-emitting layer 170 ... p-side superlattice layer 180 ... p-type intermediate layer 181 ... 1 p-type GaN layer 182 ... second p-type GaN layer 190 ... p-type contact layer 190a ... first surface 190b ... second surface N1 ... n-electrode P1 ... p-electrode

Claims (11)

an n-type semiconductor layer forming step of forming an n-type semiconductor layer;
A light emitting layer forming step of forming a light emitting layer on the n-type semiconductor layer;
A p-type semiconductor layer forming step of forming a p-type semiconductor layer on the light emitting layer;
In the method for producing a group III nitride semiconductor light-emitting device having:
The p-type semiconductor layer forming step includes:
A p-type cladding layer forming step of forming a p-type cladding layer on the light emitting layer by supplying a first source gas containing at least a group III element and a dopant gas;
A p-type intermediate layer forming step of forming a p-type intermediate layer on the p-type cladding layer by supplying the first source gas and the dopant gas;
After the p-type intermediate layer forming step, the supply of the first source gas is stopped and the dopant gas supply step of supplying the dopant gas,
A p-type contact layer forming step of forming a p-type contact layer on the p-type intermediate layer by supplying the first source gas and the dopant gas after the dopant gas supplying step;
I have a,
The molar ratio of the dopant gas to the first source gas in the dopant gas supply step is
Greater than the molar ratio of the dopant gas to the first source gas in the p-type intermediate layer forming step,
The molar ratio of the dopant gas to the first source gas in the p-type contact layer forming step is
Greater than the molar ratio of the dopant gas to the first source gas in the p-type intermediate layer forming step,
The flow rate of the first source gas in the p-type contact layer forming step is
Less than the flow rate of the first source gas in the p-type intermediate layer forming step,
The flow rate of the dopant gas in the p-type contact layer forming step is
More than the flow rate of the dopant gas in the p-type intermediate layer forming step,
The p-type contact layer has a thickness of 0.5 nm to 10 nm,
Mg concentration of the p-type contact layer is 1 × 10 ²⁰ cm ⁻³ or more and 1 × 10 ²² cm ⁻³ or less,
The group III nitriding characterized in that the change rate of Mg concentration of the p-type contact layer is 5 × 10 ¹⁸ cm ^-3 · nm ^-1 or more and 1 × 10 ²⁰ cm ^-3 · nm ^-1 or less. For manufacturing a semiconductor light emitting device. In the manufacturing method of the group III nitride semiconductor light-emitting device according to claim 1 ,
The flow rate of the dopant gas in the dopant gas supply step is
The method for producing a group III nitride semiconductor light-emitting device according to claim multi Ikoto <br/> than the flow rate of the dopant gas in said p-type intermediate layer forming step. In the manufacturing method of the group III nitride semiconductor light-emitting device according to claim 1 ,
The flow rate of the dopant gas in the dopant gas supply step is
The method for producing a group III nitride semiconductor light emitting element characterized the flow rate from the low Ikoto <br/> of the dopant gas in said p-type contact layer formation step. In the manufacturing method of the group III nitride semiconductor light-emitting device according to claim 1 ,
The flow rate of the dopant gas in the dopant gas supply step is
The method for producing a group III nitride semiconductor light-emitting device according to claim multi Ikoto <br/> than the flow rate of the dopant gas in said p-type contact layer formation step. In the manufacturing method of the group III nitride semiconductor light-emitting device according to any one of claims 1 to 4 ,
In the dopant gas supply step,
A method for producing a group III nitride semiconductor light-emitting device, wherein the supply amount of the dopant gas is gradually increased. In the manufacturing method of the group III nitride semiconductor light-emitting device according to any one of claims 1 to 5 ,
The supply amount of the first source gas in the p-type contact layer forming step is as follows:
A method for producing a Group III nitride semiconductor light-emitting device, characterized in that it is equal to the supply amount of the first source gas in the p-type intermediate layer forming step. In the manufacturing method of the group III nitride semiconductor light-emitting device according to any one of claims 1 to 6 ,
In the p-type intermediate layer forming step and the p-type contact layer forming step,
Supplying a third source gas containing nitrogen atoms;
In the dopant gas supply step,
A method of manufacturing a group III nitride semiconductor light-emitting device, wherein the supply of the third source gas is stopped. In the manufacturing method of the group III nitride semiconductor light-emitting device according to any one of claims 1 to 7 ,
The p-type intermediate layer forming step includes:
A first p-type intermediate layer forming step of forming a first p-type intermediate layer on the p-type cladding layer;
A second p-type intermediate layer forming step of forming a second p-type intermediate layer on the first p-type intermediate layer;
A method for producing a Group III nitride semiconductor light-emitting device, comprising: In the manufacturing method of the group III nitride semiconductor light-emitting device according to any one of claims 1 to 8 ,
The dopant gas supply step includes
A method for producing a Group III nitride semiconductor light-emitting device, comprising an implementation period within a range of 1 second to 60 seconds. In the manufacturing method of the group III nitride semiconductor light-emitting device according to any one of claims 1 to 9 ,
The first source gas is
A gas containing a gallium atom as the group III element,
The dopant gas is
A method for producing a group III nitride semiconductor light-emitting device, wherein the gas contains a magnesium atom. In the manufacturing method of the group III nitride semiconductor light-emitting device according to any one of claims 1 to 10 ,
In the p-type intermediate layer forming step,
Supply at least nitrogen gas as carrier gas,
A method for producing a Group III nitride semiconductor light-emitting device, wherein the nitrogen gas occupying the carrier gas is in the range of 30% to 80% in terms of molar ratio.

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